progress on column_expression and table_column_expression

source/orm/query/criteria/binary_criteria.cpp

@@ -25,7 +25,7 @@ const criteria_value& binary_criteria::value() const {
   return value_;
 }
 
-binary_column_criteria::binary_column_criteria(table_column  left_column, const binary_operator operand, table_column  right_column)
+binary_column_criteria::binary_column_criteria(const table_column& left_column, const binary_operator operand, const table_column& right_column)
 : left_column_(std::move(left_column))
 , operator_(operand)
 , right_column_(std::move(right_column)){}

source/orm/query/expression/table_column_expression.cpp

@@ -2,8 +2,8 @@
 #include "matador/query/expression/expression_visitor.hpp"
 
 namespace matador::query {
-table_column_expression::table_column_expression(table_column col)
-: column_(std::move(col)){
+table_column_expression::table_column_expression(const table_column& col)
+: column_(col){
 }
 
 void table_column_expression::accept(expression_visitor &visitor) const {

source/orm/query/expression_evaluator.cpp

@@ -50,7 +50,7 @@ void expression_evaluator::visit(const value_expression& node) {
   expression_.append(v.result);
 }
 
-void expression_evaluator::visit(const placeholder_expression& node) {
+void expression_evaluator::visit(const placeholder_expression& /*node*/) {
   query_.bind_vars.emplace_back(std::string("value_") + std::to_string(query_.bind_vars.size() + 1));
   expression_.append(dialect_.next_placeholder(query_.bind_vars));
 }